The human eye equipped with contact lenses, must be protected from microbial infection. One of the problems associated with these lenses resides in their maintenance product. Besides a simplicity of use, this latter requires qualities of microbiological efficiency and cleaning properties.
To this effect, there exist several methods which are classified according to their method of action in two categories, to be known as chemical and physical.
These processes nevertheless have certain inconveniences.
The chemical procedures use isotonic and sterilizing solutions containing preservatives, such as chlorhexidine and gluconate, mercury derivates or quaternary ammonium. The use of these solutions imposes numerous constraining operations on the user. Moreover, reactions of toxicity and ocular irritation are not uncommon.
A second method consists of treating the lenses with a 3% hydrogen peroxide solution. This procedure is efficient from the point of view of germ destruction, but the solution used must be neutralized with a reducing agent or a strong burning in the eye of the user may be provoked.
In the category of physical methods, there can be mentioned boiling, which is a confirmed process for sterilization of water, but which has the disadvantage, in the case of contact lenses, of provoking a lens cloudiness due to the denaturation of the muco-proteic material.
At present, there is thus no method which brings together simplicity of use and absence of undesirable secondary effects.